使用Java代写一个代码生成器。
Requirement
In this assignment, we will implement code generation for part of the
language. The abstract syntax shown below has been modified to indicate which
part of the language we need to implement now and how they map into JVM
elements.
Program ::= Name List
class Name implements Runnable {
variables declared in List
public Name(String[]args) {
initialize instance variables with values from args.
}
public static void main(String[] args) {
Name instance = new Name(args);
instance.run();
}
public void run() {
declarations and statements from block
}
}
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The provided version of CodeGenVisitor.java also include a partially complete
version of visitProgram. It is sufficient to generate code for an empty
program. A test case in CodeGenVisitorTest with an empty program has been
provided to illustrate how to put the pieces together, get useful output, etc.
Use it to ensure that you have asm set up properly and as a starting point for
your own tests. You will need asm and asm.util.
Because this fragment of our language does not have output, two routines,
genPrint and genPrintTOS have been included with the provided version of
CodeGenVisitor.java. These routines generate code to print a String and print
the value on top of the stack (without consuming it), respectively. The
CodeGenVisitor has a variable DEVEL and a variable GRADE that are set via
parameters to the constructor. Both routines take a Boolean parameter that
indicates whether these routines generate code or just to nothing. By adding
these in appropriate places, you can easily generate code instrumented to show
you what it is doing, and turn it off later.
In order to grade this assignment, we will be comparing the sequence of values
written in assignment statements. (See assignment statement above.) Please
follow directions exactly. This should be the ONLY call to genPrint of
genPrintTOS that is passed the value of GRADE. You may insert calls with DEVEL
anywhere you want. We will test with DEVEL = false and GRADE = true. The only
output from the execution of your generated code should be these print
statements.
It is difficult to write unit tests for these programs, nevertheless, Junit
provides a convenient way to manage tests, even if they cannot easily
automatically check the output. You should also be able to run your generated
classfiles as a Java application program with the arguments on the command
line.
Provided code
CodeGenVisitor.java starter code for code generation. visitProgram sets up the
class and generates the main method and constructor, and the framework of the
run method. You will need to make some changes, but it should compile and deal
with the empty program as is. Implement all the methods marked “Implement
this”.
CodeGenUtils.java some routines helpful during code generation
cop5556sp17.AST.Type.java A few useful modifications from the previous
version.
Turn in
CodeGenVisitor.java, CodeGenVisitorTest.java, Parser.java, Scanner.java,
SymbolTable.java, TypeCheckVisitor.java, all the classes in cop5555617.AST.
Troubleshooting Hints
If there are exceptions in the call to visitMaxs, you can temporarily replace
cw=newClassWriter(ClassWriter.COMPUTE_FRAMES);
at the beginning of visitProgram with
cw=newClassWriter(0);
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This will not yield a runnable class file, but it will allow you see the code
that is being generated.
The JVM lecture also included some troubleshooting tips.
